Simple, secure encryption and decryption for Python 2.7 and 3
What Does Simple Crypt Do?
Simple Crypt encrypts and decrypts data. It has two functions, encrypt and decrypt:
from simplecrypt import encrypt, decrypt ciphertext = encrypt('password', plaintext) plaintext = decrypt('password', ciphertext)
That’s it. You can see the implementation on github.
Why Should I Use Simple Crypt?
- It uses standard, well-known algorithms, closely following the recommendations here.
- The established, efficient pycrypto library provides the algorithm implementations (the cipher used is AES256).
- It includes a check (an HMAC with SHA256) to warn when ciphertext data are modified.
- It tries to make things as secure as possible when poor quality passwords are used (PBKDF2 with SHA256, a 256 bit random salt (increased from 128 bits in release 3.0.0), and 100,000 rounds (increased from 10,000 in release 4.0.0)). But that doesn’t mean you should use a poor password!
- Using a library, rather than writing your own code, means that we have less solutions to the same problem. That means more chance of finding bugs, which means more reliable, more secure code.
- If simple-crypt does have a bug, the use of a header in the ciphertext data will help support an upgrade path (I can’t promise full backwards support, because any solution will depend on the attack, but at least the needed information is present).
What Else Should I Know?
You must also install pycrypto. Note that pycrypto has parts written in C so requires a full python install. On some unix systems that may mean adding a package like python-dev from your package manager.
In Python 3 the outputs from encrypt and decrypt are bytes. If you started with string input then you can convert the output from decrypt using .decode('utf8'):
mystring = decrypt('password', ciphertext).decode('utf8')
Later versions can decrypt data from previous versions, but data encrypted by later (major) versions cannot be decrypted by earlier code (instead, an error is raised asking the user to update to the latest version).